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Reactive Power Calculation
Rootech supports two methods for accurate calculation of reactive power.
Method 1: General Calculation
Method 1 is used to obtain reactive power, and apparent power by using calculation of vector
apparent power.
=
T
a
a
a
dt
t
I
t
V
T
P
0
)
(
)
(
1
,
=
T
b
b
b
dt
t
I
t
V
T
P
0
)
(
)
(
1
,
=
T
c
c
c
dt
t
I
t
V
T
P
0
)
(
)
(
1
c
b
a
P
P
P
P
+
+
=
+
=
T
a
T
a
a
dt
t
I
t
V
T
Q
0
4
)
(
)
(
1
,
+
=
T
b
T
b
b
dt
t
I
t
V
T
Q
0
4
)
(
)
(
1
,
+
=
T
c
T
c
c
dt
t
I
t
V
T
Q
0
4
)
(
)
(
1
c
b
a
Q
Q
Q
Q
+
+
=
2
2
Q
P
S
+
=
,
S
P
PF
=
2
2
a
a
a
Q
P
S
+
=
,
2
2
b
b
b
Q
P
S
+
=
,
2
2
c
c
c
Q
P
S
+
=
,
a
a
a
S
P
PF
=
,
b
b
b
S
P
PF
=
,
c
c
c
S
P
PF
=
Fig 2.5 P, Q[according to general calculation]
Note
When phase difference between voltage and current is within 90 degree of lead and lag, power
factor is positive. However, when phase difference is more than 90 degree[miswiring,
regeneration], power factor and active power are negative.